Request help with ... something

The attached is a window grab of a window that, all by itself, pops up on my system. I just close the window but I'd like to know how to prevent this from happening at all.

Thanks in advance.

ETA: Firefox on Windows 10.

Attached Images

Capture13.jpg (44.6 KB)

via International Skeptics Forum http://bit.ly/2RpjxN7